Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrates concerning the man who comes to his wife while she is menstruating; he said: "If he comes to her during the blood, he should give one dinar in charity, and if he comes to her other than during the blood, he should give half a dinar in charity."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحيض / 1529